package queuedemo;

/**
 * 数组 实现的循环队列
 */
class MyCircularQueue {

    public int[] elem;
    public int front;//头
    public int rear;//尾

    public MyCircularQueue(int k) {
        //elem = new int[k+1];
        elem = new int[k];
    }

    /**
     * 入队
     * @param value
     * @return
     */
    public boolean enQueue(int value) {
        if(isFull()) {
            return false;
        }
        this.elem[rear] = value;
        rear = (rear+1)%elem.length;
        return true;
    }

    /**
     * 出队
     * @return
     */
    public boolean deQueue() {
        if(isEmpty()) {
            return false;
        }
        front = (front+1)%elem.length;;
        return true;
    }

    /**
     * 获取队头元素
     * @return
     */
    public int Front() {
        if(isEmpty()) {
            return -1;
        }
        return elem[front];
    }

    /**
     * 获取队尾元素
     * @return
     */
    public int Rear() {
        if(isEmpty()) {
            return -1;
        }
        int index = (rear == 0) ? elem.length-1 : rear-1;
        return elem[index];
    }

    /**
     * 判断是否为空
     * @return
     */
    public boolean isEmpty() {
        return rear == front;
    }

    /**
     * 判断是否为满
     * @return
     */
    public boolean isFull() {
        if( (rear+1) % elem.length == front) {
            return true;
        }
        return false;
    }
}